Abstract: In a switching regulator, input voltage is applied to a primary coil of a transformer through a location between a collector and an emitter of a switching transistor connected in series to the primary coil of the transformer. A pair of output terminals are connected to a secondary coil of the transformer through a rectifier smoothing circuit. A comparator compares output voltage occurring between the output terminals with reference voltage to generate an output signal. On the basis of the output signal, a control circuit applies a drive control signal to a base of the switching transistor. The reference voltage is given such that first voltage maintained substantially constant and second voltage such as outside input voltage or the like capable of being regulated over a relatively large varying width are added to each other.